Aqueous compositions with polyvalent metal ions and dispersed polymers

ABSTRACT

There is provided a composition comprising (a) at least one aqueous polymer dispersion, wherein said polymer is formed from a monomer mix comprising one or more carboxylic acid functional monomers; (b) at least one swelling agent; and (c) at least one polyvalent metal ion; wherein said composition is formed by a process comprising the step of forming a preliminary admixture of said dispersion (a) with some or all of said swelling agent (b), wherein the ratio of equivalents of polyvalent metal ions in said preliminary admixture to equivalents of carboxylic acid functional groups in said preliminary admixture is 0.25 or less.

BACKGROUND

A variety of useful compositions contain at least one polymer dispersedin water and at least one polyvalent metal cation. In some of suchcompositions, the polymer has acid functionality. Such compositions areuseful for a variety of purposes, for example as ingredients in leathertreatments and floor polishes. In the past, many known examples of suchcompositions had relatively low level of polyvalent cation, though, insome cases, the usefulness of such a composition is improved if thecomposition has a higher level of polyvalent metal cation. Higher levelsof polyvalent cation are considered to improve the properties of suchcompositions; for example, coatings such as, for example, floorpolishes, are thought to be more durable if higher levels of polyvalentmetal cation are used. One method of increasing the level of polyvalentmetal cation in such compositions is disclosed in U.S. Pat. No.5,149,745, which teaches reacting an acid-functional polymer with atransition metal compound at a temperature above the glass transitiontemperature (Tg) of the polymer. It is desired to provide compositionswith relatively high levels of polyvalent metal cation that can be madeby alternative methods.

STATEMENT OF THE INVENTION

In a first aspect of the present invention, there is provided acomposition comprising

-   (a) at least one aqueous polymer dispersion, wherein said polymer is    formed from a monomer mix comprising 5-50% by weight based on the    weight of said monomer mix, of one or more carboxylic acid    functional monomers;-   (b) 1 to 10 parts by weight of at least one swelling agent, based on    100 parts by weight of said monomer mix; and-   (c) at least one polyvalent metal ion;    wherein the ratio of equivalents of polyvalent metal ions in said    composition to equivalents of carboxylic acid functional groups in    said composition is 0.4 or more; and wherein said composition is    formed by a process comprising the step of forming a preliminary    admixture of said dispersion (a) with some or all of said swelling    agent (b), wherein the ratio of equivalents of polyvalent metal ions    in said preliminary admixture to equivalents of carboxylic acid    functional groups in said preliminary admixture is 0.25 or less.

In a second aspect of the present invention, there is provided a processof forming a composition, comprising the steps of

-   (a) forming at least one aqueous polymer dispersion, by a process    comprising polymerization of a monomer mix comprising 5-50% by    weight based on the weight of said monomer mix, of one or more    carboxylic acid functional monomers;-   (b) forming a preliminary admixture by admixing said dispersion (a)    with 1 to 10 parts by weight of at least one swelling agent, based    on 100 parts by weight of said monomer mix, wherein the ratio of    equivalents of polyvalent metal ions in said preliminary admixture    to equivalents of carboxylic acid functional groups in said    preliminary admixture is 0.25 or less; and-   (c) forming a subsequent admixture by admixing said preliminary    admixture (b) with at least one polyvalent metal ion, wherein the    ratio of equivalents of polyvalent metal ions in said subsequent    admixture to equivalents of carboxylic acid functional groups in    said subsequent admixture is 0.4 or more.

DETAILED DESCRIPTION

As used herein “(meth)acrylate” and “(meth)acrylic” mean, respectively,“acrylate or methacrylate” and “acrylic or methacrylic.”

As used herein, a material is “aqueous” if that material contains atleast 25% water by weight, based on the total weight of that material.

As used herein, a “dispersion” contains, sometimes among otheringredients, discrete particles that are suspended in a continuousmedium. When the continuous medium contains at least 50% water byweight, based on the weight of the continuous medium, the dispersion issaid to be an “aqueous dispersion,” and the continuous medium is said tobe an “aqueous medium.” When at least some of the suspended discreteparticles in the dispersion contain one or more polymers, the dispersionis said herein to be a “polymer dispersion.” Thus, an “aqueous polymerdispersion” contains some polymer-containing particles suspended in acontinuous medium that is at least 50% water.

The group of polymer particles in a sample of an aqueous polymerdispersion have a variety of sizes. In some cases, the polymer particlesare spherical or nearly spherical; in such cases their sizes canusefully be characterized by their diameters, and the group of polymerparticles can be usefully characterized by the average diameter of theparticles. One useful method of measuring the average diameter of theparticles is light scattering. In some embodiments, the average diameterof the particles is 80 nm or larger; or 100 nm or larger; or 125 nm orlarger. Independently, in some embodiments, the average diameter of theparticles is 1,000 nm or smaller; or 500 nm or smaller; or 250 nm orsmaller. In some embodiments, the average diameter of the particles issmaller than 150 nm.

The polymer of the aqueous polymer dispersion of the present inventionis formed by the polymerization of monomers; the aggregate of allmonomers used to form the polymer is known herein as the “monomer mix.”Monomers in the monomer mix may be of any type and may polymerized byany method or mechanism.

In the practice of the present invention, the monomer mix contains 5% ormore by weight of one or more carboxylic acid functional monomers, basedon the weight of the monomer mix. In some embodiments, the monomer mixcontains 7% or more; or 9% or more, by weight of one or more carboxylicacid functional monomers, based on the weight of the monomer mix. In thepractice of the present invention, the monomer mix contains 50% or lessby weight of one or more carboxylic acid functional monomers, based onthe weight of the monomer mix. In some embodiments of the presentinvention, the monomer mix contains 20% or less by weight of one or morecarboxylic acid functional monomers, based on the weight of the monomermix. In some embodiments, the monomer mix contains 15% or less; or 12%or less, by weight of one or more carboxylic acid functional monomers,based on the weight of the monomer mix.

Carboxylic acid functional monomers are compounds capable ofpolymerization that contain at least one carboxylic acid group. Thecarboxylic acid group may be in the form of a neutral carboxylic acidgroup, in the form of a carboxylate ion, or in any mixture orcombination thereof. In some embodiments, carboxylic acid functionalmonomers are used that have carboxylic acid functional groups, and thecarboxylic acid functional groups are not removed or altered during theprocess of polymerization. Also contemplated for use in the presentinvention are monomers with other functional groups that, afterpolymerization, are converted to carboxylic acid functional groups.

The monomer mix of the present invention contains monomers other thancarboxylic acid functional monomers, known herein as “non-carboxylmonomers.” The non-carboxyl monomer or monomers may be of any type thatis capable of forming a copolymer with the carboxylic acid functionalmonomers that are used. Copolymer, as used herein, refers to a polymermade from two or more different monomers that react together to form apolymer. Copolymers may have any structure; for example, the differentmonomers may be arranged randomly, in a pattern (such as, for example,alternation), in blocks, in branches, in a star, or in any combinationthereof.

In some embodiments, some or all of the monomers in the monomer mix arevinyl monomers (i.e., monomers that each contain at least one vinylgroup).

Some suitable carboxylic acid functional vinyl monomers are, forexample, vinyl compounds with at least one carboxylic acid functionalgroup, such as, for example, alpha, beta monoethylenically unsaturatedacids; partial esters of unsaturated aliphatic dicarboxylic acids andthe alkyl half esters of such acids; and mixtures thereof. Some suitablealpha, beta monoethylenically unsaturated acids are, for example, maleicacid, fumaric acid, aconitic acid, crotonic acid, citraconic acid,acryloxypropionic acid, acrylic acid, methacrylic acid (MAA), itaconicacid, and mixtures thereof MAA is known to be a suitable alpha, betamonoethylenically unsaturated acid. Some suitable alkyl half esters ofunsaturated aliphatic dicarboxylic acids are, for example, the alkylhalf esters of itaconic acid, fumaric acid and maleic acid. Somesuitable alkyl groups for such alkyl half esters are, for example, alkylgroups with 1 to 6 carbon atoms. Some examples of such alkyl half estersare methyl acid itaconate, butyl acid itaconate, ethyl acid fumarate,butyl acid fumarate, methyl acid maleate, and mixtures thereof.

Some suitable non-carboxyl vinyl monomers are, for example, vinylaromatic monomers; alkyl esters of (meth)acrylic acid; nonionogenicvinyl monomers that are polar or polarizable; esters of hydroxy vinylmoieties with carboxylic acids; other non-carboxyl ethylenicallyunsaturated compounds; and mixtures thereof.

Some suitable vinyl aromatic monomers are, for example, alpha, betamonoethylenically unsaturated aromatic monomers. Some suitable alpha,beta monoethylenically unsaturated aromatic monomers are, for example,styrene (Sty), vinyl toluene, 2-bromo styrene, o-bromo styrene, p-chlorostyrene, o-methoxy styrene, p-methoxy styrene, allyl phenyl ether, allyltolyl ether, alpha-methyl styrene, and mixtures thereof. Styrene isknown to be a suitable vinyl aromatic monomer. In some embodiments, themonomer mix contains at least one vinyl aromatic monomer, in an amountby weight, based on the weight of the monomer mix, of 15% or more, or25% or more. Independently, in some embodiments, the monomer mixcontains at least one vinyl aromatic monomer, in an amount by weight,based on the weight of the monomer mix, of 55% or less, or 45% or less.

Some suitable alkyl esters of (meth)acrylic acid are, for example, thosein which the alkyl group has 20 or fewer carbon atoms, or 12 or fewercarbon atoms, or 8 or fewer carbon atoms. The alkyl group in suitablealkyl esters of (meth)acrylic acid may be linear, branched, cyclic, orany combination or mixture thereof. Some examples of suitable alkylesters of (meth)acrylic acid are methyl methacrylate (MMA), methylacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate (BA),butyl methacrylate (BMA), iso-butyl methacrylate (IBMA), 2-ethylhexylacrylate, n-octyl acrylate, sec-butyl acrylate, cyclopropylmethacrylate, isobornyl methacrylate, and mixtures thereof. In someembodiments, the monomer mix contains BA, MMA, or a mixture thereof.

In some embodiments, the monomer mix contains at least one alkylacrylate, in an amount by weight, based on the weight of the monomermix, of 10% or more, or 20% or more. In some embodiments, the monomermix contains at least one alkyl acrylate, in an amount by weight, basedon the weight of the monomer mix, of 60% or less, or 50% or less.

In some embodiments, the monomer mix contains at least one alkylmethacrylate, in an amount by weight, based on the weight of the monomermix, of 4% or more, or 8% or more. In some embodiments, the monomer mixcontains at least one alkyl methacrylate, in an amount by weight, basedon the weight of the monomer mix, of 45% or less, or 35% or less.

In some embodiments, the monomer mix contains at least one nonionogenicvinyl monomer that is polar or polarizable. Some examples of suchmonomers are acrylonitrile, methacrylonitrile, cis- andtrans-crotononitrile, alpha-cyanostyrene, alpha-chloroacrylonitrile,ethyl vinyl ether, isopropyl vinyl ether, isobutyl- and butyl-vinylether, diethylene glycol vinyl ether, decyl vinyl ether, vinyl acetate,hydroxyalkyl (meth)acrylates such as 2-hydroxy ethyl methacrylate,2-hydroxyethyl acrylate, 3-hydroxy propyl methacrylate, butanediolacrylate, 3-chloro-2-hydroxypropyl acrylate, 2-hydroxypropyl acrylate,2-hydroxypropyl methacrylate, and mixtures thereof.

Some additional examples of nonionogenic vinyl monomers that are polaror polarizable are those that contain sulfur. Among sulfur-containingnonionogenic vinyl monomers that are polar or polarizable are vinylthiols such as, for example, 2-mercaptopropyl methacrylate,2-sulphoethyl methacrylate, methyl vinyl thiol ether, and propyl vinylthiol ether. In some embodiments, the monomer mix contains one or moresulfur-containing nonionogenic vinyl monomers that are polar orpolarizable. In other embodiments, the monomer mix contains nosulfur-containing nonionogenic vinyl monomers that are polar orpolarizable.

Some further examples of nonionogenic vinyl monomers that are polar orpolarizable are ethylenically unsaturated monomers that contain at leastone acetoacetate or acetoacetamide grouping. In some embodiments of thepresent invention, the monomer mix includes one or more monomers thatcontain at least one acetoacetate or acetoacetamide grouping. In otherembodiments of the present invention, the monomer mix excludes monomersthat contain at least one acetoacetate or acetoacetamide grouping.

In some embodiments, the monomer mix contains at least one ester of ahydroxy vinyl moiety with a carboxylic acid. In some embodiments, thecarboxylic acid portion of such an ester is selected from the aromaticand aliphatic carboxylic acids. Suitable aliphatic carboxylic acidsinclude, for example, those with 1 to 18 carbon atoms. Such aliphaticcarboxylic acids include, for example, formic, acetic, propionic,n-butyric, n-valeric, palmitic, stearic, phenyl acetic, benzoic,chloroacetic, dichloroacetic, gamma-chloro butyric, 4-chlorobenzoic,2,5-dimethyl benzoic, o-toluic, 2,4,5-trimethoxy benzoic, cyclobutanecarboxylic, cyclohexane carboxylic, 1-(p-methoxy phenyl)cyclohexanecarboxylic, 1-(p-tolyl)-1-cyclopentane carboxylic, hexanoic, myristic,and p-toluic acids. The hydroxy vinyl moiety of such an ester may be,for example, selected from hydroxy vinyl compounds such as hydroxyethylene, 3-hydroxy-pent-1-ene, 3,4-dihydroxybut-1-ene, and3-hydroxy-pent-1-ene.

It is to be understood herein that, when a compound is described as anester of a certain hydroxy moiety and a particular acid, such adescription refers to the structure of the ester and not necessarily tothe actual method by which the ester is made.

In some embodiments, the monomer mix contains one or more monomers withat least one sulfur-containing acid functional group. Sulfur-containingacid functional groups include sulfate and sulfonate groups. In someembodiments, the monomer mix contains no monomers with sulfate groups orsulfonate groups. In some embodiments, the monomer mix includes nomonomers with any sulfur-containing acid functional group. In someembodiments, the monomer mix includes no monomers that contain sulfur.

An aqueous polymer dispersion of the present invention may be made byany of a wide variety of methods. In some embodiments, the polymer maybe formed by any polymerization method and then dispersed in water. Insome embodiments, the polymer is formed as suspended particles in anaqueous medium, for example, by suspension polymerization, emulsionpolymerization, microemulsion polymerization, or a combination thereof.

In some embodiments, the polymer is formed by emulsion polymerization.The practice of emulsion polymerization is discussed in detail in D. C.Blackley, Emulsion Polymerization (Wiley, 1975). For example, themonomers may be emulsified with anionic or nonionic dispersing agents;about 0.5% to 10% thereof on the weight of total monomers being used. Apolymerization initiator of the free radical type, such as, for example,ammonium or potassium persulphate, may be used alone or in conjunctionwith an accelerator, such as, for example, potassium metabisulphate orsodium thiosulphate. The initiator and accelerator (if used), commonlyreferred to as catalysts, may conveniently be used in proportions of0.5% to 2% each based on the weight of monomers to be copolymerized. Thepolymerization temperature may for example be from room temperature to90° C., or more, as is conventional.

Examples of emulsifiers which are suited to the polymerization processuseful in this invention include, for example, alkaline metal andammonium salts of alkyl, aryl, alkyl-substituted aryl andaryl-substituted alkyl sulphonates, sulphates and polyether sulphates,such as sodium vinyl sulphonate, and sodium methallyl sulphonate; thecorresponding phosphates and phosphonates, such as phosphoethylmethacrylate; and alkoxylated fatty acids, esters, alcohols, amines,amides and alkylphenols.

Chain transfer agents, including, for example, mercaptans,polymercaptans and polyhalogen compounds, are sometimes used in thepolymerization mixture to control polymer molecular weight.

Among embodiments in which at least one polymer of the present inventionis made by emulsion polymerization, any of the various types of emulsionpolymerization may be used. For example, in some embodiments, a “singlestage” emulsion polymerization is used, in which the monomer mix,sometimes in emulsified form, is either added all at once to thereaction container or is added gradually to the reaction containerduring the polymerization reaction. Alternatively, in some embodiments,a “multi-stage” emulsion polymerization is used, in which the monomermix is provided as two or more portions of different compositions; aftereach portion is polymerized, all or part of the resulting polymer iskept in or is placed into a vessel, and a subsequent portion of monomermix is added to that vessel and polymerized.

As stated herein above, “monomer mix” is contemplated herein to mean theaggregate of all monomers used to make the polymer of the presentinvention, regardless of the physical form in which the monomer mix isused. For example, in some embodiments, the monomer mix is provided as asingle physical mixture in a single container. In some embodiments, themonomer mix is provided as two or more mixtures (which may be the sameas each other or may be different from each other) of monomers in two ormore different containers.

It is sometimes useful to characterize the aqueous polymer dispersion byits minimum film formation temperature MFT (also sometimes called“MFFT”). MFT can be measured, for example, by ASTM method D2354-98. Whenthe aqueous polymer dispersion is dried, the minimum temperaturenecessary for the dry polymer to form a film is the MFT. In the practiceof the present invention, it is useful to characterize the aqueouspolymer dispersion in the absence of added swelling agent, added metalcation, and added adjuvant. In general, aqueous polymer dispersions ofthe present invention may have any MFT; a person practicing the presentinvention can readily choose an aqueous polymer dispersion with MFTappropriate for the intended use. In some embodiments, the aqueouspolymer dispersion has MFT of 40° C. or higher, or 60° C. or higher.

The practice of the present invention involves the use of at least onepolyvalent metal cation, which means herein a metal cation with chargeof +2 or higher. Suitable polyvalent metal cations are, for example,polyvalent cations of alkaline earth metals and polyvalent cations oftransition metals. Among the suitable metals whose polyvalent cationsare suitable for use in the present invention are, for example,magnesium, arsenic, mercury, cobalt, iron, copper, lead, cadmium,nickel, chromium, aluminum, tungsten, tin, zinc, zirconium, and mixturesthereof. In some embodiments, one or more of zinc, copper, magnesium,and mixtures thereof are used. In some embodiments, zinc is used. Insome embodiments, magnesium is used.

In some embodiments, at least one polyvalent metal ion is used in theform of a complex. Some suitable complexes include, for example,carbonates, bicarbonates, and glycinates. In some embodiments, it isuseful to solubilize such a complex prior to adding it to an aqueouspolymer dispersion. One method to solubilize such a complex is to addthe complex to dilute aqueous ammonia; the result is named by inserting“ammonia” into the name of the original complex. For example, whencadmium glycinate is solubilized by addition to aqueous ammonia, theresult is named “cadmium ammonia glycinate.” Similarly solubilizedcomplexes are zinc ammonia glycinate and zinc ammonia bicarbonate.

In some embodiments, the polyvalent metal cation, prior to its additionto the composition, is in the form of an insoluble metal compound.“Insoluble,” as used herein, means a compound that has solubility inwater of less than 4.2 g of compound in 100 g of water. Suitableinsoluble metal compounds include, for example, oxides, hydroxides,carbonates, acetates, and mixtures thereof. One suitable insoluble metalcompound is zinc oxide.

The amount of polyvalent metal cation in the composition of the presentinvention is characterized by the number of equivalents. For each typeof polyvalent metal cation that is present, the number of equivalents ofthat polyvalent metal cation is the number of moles of the cation thatis present, multiplied by the valency of the cation. One mole ofdivalent metal cations provides two equivalents; one mole of trivalentmetal cations provides three equivalents; and so on.

In compositions of the present invention, the ratio of the equivalentsof polyvalent metal cations present in the composition to theequivalents of carboxyl groups (including both carboxylate groups andneutral carboxyl groups) is 0.4 or higher. In some embodiments, thatratio is 0.6 or higher; or 0.7 or higher; or 0.8 or higher.Independently, in some embodiments, that ratio is 1.2 or lower; or 1.0or lower; or 0.9 or lower.

The practice of the present invention involves the use of at least oneswelling agent. A “swelling agent” as used herein is a compound thatinteracts with a polymer in a way that increases the flexibility of thatpolymer. In some embodiments, the swelling agent is an organic compound.Independently, in some embodiments, the swelling agent is anon-polymeric compound. In some embodiments, the swelling agent is anon-polymeric organic compound.

While the present invention may be practiced with any polyvalent metalcation, one way of testing whether a compound of interest suitable as aswelling agent for a particular aqueous polymer dispersion is to performa zinc uptake test, as described in the Examples herein below, with thataqueous polymer dispersion and the compound of interest. A compound ofinterest that results in a detectable decrease in zinc precipitate is asuitable swelling agent.

An alternative method of testing whether a compound of interest issuitable as a swelling agent for a particular aqueous polymer dispersionis to measure the MFT (as defined herein above) of that aqueous polymerdispersion with and without the presence of the compound of interest.That is, the MFT of the aqueous polymer dispersion itself is measured.Also, the compound of interest is admixed with the aqueous polymerdispersion, and the MFT of the admixture is measured. If the MFT of theadmixture is lower than the MFT of the aqueous polymer dispersionitself, then the compound of interest is suitable as a swelling agent ofthe present invention.

Among the suitable swelling agents that are organic compounds, a widevariety are contemplated. Some suitable swelling agents are, forexample, solvents, surfactants, dispersants, plasticizers, orcoalescents. Some suitable swelling agents are highly volatile, such as,for example, many solvents. Some suitable swelling agents are moderatelyvolatile, such as, for example, coalescents. Some suitable swellingagents are only slightly volatile or are non-volatile, such as, forexample, many plasticizers, surfactants, and dispersants. In someembodiments, the swelling agent includes one or more plasticizers, oneor more coalescents, or a mixture thereof.

Swelling agents suitable in the present invention include, for example,alcohols, ether compounds, carboxylate esters, phosphate esters, amides,and mixtures thereof.

Some alcohols suitable as swelling agents include, for example,aliphatic alcohols with 2 to 10 carbon atoms. Some suitable alcoholsare, for example, isopropanol, butanol, 2-ethylhexanol, and pine oil.

Some ether compounds suitable as swelling agents are, for example, alkyland aromatic ethers of monoalkylene glycols and multialkylene glycols,where “multi-” means “di-” or “tri-” or higher; alkylene glycol means aglycol with 2 or 3 or more carbon atoms; and in the case of alkylethers, the alkyl group has 1, 2, or more carbon atoms. Some suitablealkyl ethers of multialkylene glycols are, for example, diethyleneglycol ethyl ether, dipropylene glycol methyl ether, and mixturesthereof.

Further ether compounds suitable as swelling agents are, for example,ether alcohols, which are compounds containing at least one ether linkand at least one hydroxyl group. Some suitable ether alcohols are, forexample, 2-butoxy ethanol and butyl carbitol.

Another group of compounds suitable as swelling agents are carboxylateesters, which are compounds containing at least one ester link.Carboxylate esters are described herein as “esters of” a hydroxylcompound and a carboxylic acid; it is to be understood that such adescription refers to the structure of the ester, whether not the esteris made by reacting that hydroxyl compound with that carboxylic acid.“Mono-hydroxyl” compound as used herein is a compound with a singlehydroxyl group. “Polyol” as used herein is a compound with two or morehydroxyl groups. “Monocarboxylic acid” as used herein is a compound witha single carboxylic acid group. “Multicarboxylic acid” as used herein isa compound with two or more carboxylic acid groups.

Some carboxylate esters suitable as swelling agents are, for example,esters of mono-hydroxyl compounds and monocarboxylic acids. Suitablemonocarboxylic acids include, for example, aromatic monocarboxylic acids(such as, for example, benzoic acid) and aliphatic monocarboxylic acids.Suitable aliphatic monocarboxylic acids include, for example, alkylmonocarboxylic acids with 4 to 8 carbon atoms. Suitable mono-hydroxylcompounds include, for example, mono-hydroxyl alkyl compounds such as,for example, those with straight or branched alkyl groups with 3 to 13carbon atoms.

Some further carboxylate esters suitable as swelling agents are, forexample, mono- and di-esters of mono-hydroxyl compounds andmulticarboxylic acids. Suitable multicarboxylic acids include, forexample, aromatic multicarboxylic acids (such as, for example, phthalicacid and trimellitic acid) and aliphatic multicarboxylic acids. Somesuitable aliphatic multicarboxylic acids are, for example, oxalic acid,fumaric acid, maleic acid, adipic acid, and pimelic acid. Suitablemono-hydroxyl compounds include, for example, mono-hydroxyl alkylcompounds such as, for example, those with straight or branched alkylgroups with 3 to 13 carbon atoms.

Also suitable are alkyl and aromatic mono- and di-esters of the glycolsdescribed herein above and monocarboxylic acids.

Additional carboxylate esters suitable as swelling agents are, forexample, mono-, di- and higher esters of alkyl polyols andmonocarboxylic acids. Suitable alkyl polyols are those with 4 or more,or 6 or more, or 8 or more, carbon atoms. Suitable monocarboxylic acidsare, for example, alkyl carboxylic acids with 3 or 4 carbon atoms. Someexamples of suitable esters are the following: Texanol™ (from EastmanChemical), mono- and di-alkyl esters of iso-octane diol, and mono- anddi-alkyl esters of butane diol.

Some phosphate esters suitable as swelling agents are, for example,trialkyl phosphates (such as, for example, tri-2-ethylhexyl phosphate),triaryl phosphates (such as, for example, tricresyl phosphate), andmixed alkyl/aryl phosphates (such as, for example, 2-ethylhexyl diphenylphosphate).

One suitable amide swelling agent is, for example, caprolactam.

Mixtures of suitable swelling agents are also suitable.

The amount of swelling agent used in the practice of the presentinvention can be characterized by the weight of swelling agent comparedto the weight of the monomer mix. For 100 parts by weight of monomermix, the amount of swelling agent is 1 or more parts by weight, or 2 ormore parts by weight, or 3 or more parts by weight, or 4 or more partsby weight. Independently, for 100 parts by weight of monomer mix, theamount of swelling agent is 10 or less parts by weight, or 7 or lessparts by weight, or 5 or less parts by weight.

In the practice of the present invention, some or all of the at leastone swelling agent is admixed with the aqueous polymer dispersion, andthe result is herein called a “preliminary admixture.” The preliminaryadmixture contains at least 1 part by weight of at least one swellingagent, based on 100 parts by weight of monomer mix. The preliminaryadmixture contains no polyvalent metal cation or contains a relativelysmall amount of polyvalent metal cation. The ratio of equivalents ofpolyvalent metal cation in the preliminary admixture to equivalents ofcarboxylic acid functional groups in the preliminary admixture is 0.25or less. In some embodiments the ratio of equivalents of polyvalentmetal cation in the preliminary admixture to equivalents of carboxylicacid functional groups in the preliminary admixture is 0.1 or less, or0.05 or less; or 0.01 or less.

The preliminary admixture may be formed by any technique, under anyconditions. In some embodiments, the preliminary admixture may be formedat elevated temperature (higher than 35° C.). In other embodiments, thepreliminary admixture may be formed at 35° C. or lower, or at 30° C. orlower.

In the practice of the present invention, subsequent to forming thepreliminary admixture, the preliminary admixture is admixed with atleast one polyalent metal cation to form a subsequent admixture. Theratio of equivalents of polyvalent metal cation in the subsequentadmixture to equivalents of carboxylic acid functional groups in thesubsequent admixture is 0.4 or more. In some embodiments, the ratio ofequivalents of polyvalent metal cation in the subsequent admixture toequivalents of carboxylic acid functional groups in the subsequentadmixture is 0.5 or more; or 0.6 or more; or 0.7 or more; or 0.8 ormore. The ratio of equivalents of polyvalent metal cation in thesubsequent admixture to equivalents of carboxylic acid functional groupsin the subsequent admixture is 1.2 or lower. In some embodiments, theratio of equivalents of polyvalent metal cation in the subsequentadmixture to equivalents of carboxylic acid functional groups in thesubsequent admixture is 1.0 or lower, or 0.9 or lower.

The subsequent admixture may be formed by any technique, under anyconditions. In some embodiments, the subsequent admixture may be formedat elevated temperature (higher than 35° C.). In other embodiments, thesubsequent admixture may be formed at 35° C. or lower, or at 30° C. orlower. Independently, in some embodiments, the subsequent admixture isformed at temperature less than the MFT of the aqueous polymerdispersion. Independently, in some embodiments, the subsequent admixtureis formed at temperature approximately equal to the MFT of the aqueouspolymer dispersion.

In some embodiments, the subsequent admixture is formed at a temperatureabove the Tg of the polymer of the aqueous polymer dispersion. By “Tg ofthe polymer” is meant herein the Tg as calculated by the Fox equation(T. G. Fox, Bulletin of the American Physical Society, series II, volume1, 1956, p. 123), based only on the monomers in the monomer mix and notbased on other ingredients admixed with the polymer. In otherembodiments, the subsequent admixture is formed at a temperature equalto or below the Tg of the polymer of the aqueous polymer dispersion,including, for example, embodiments in which the temperature offormation of the subsequent admixture is lower than the Tg of thepolymer of the aqueous polymer dispersion by a difference of 4° C. ormore, or by a difference of 10° C. or more.

In some embodiments, the subsequent admixture is formed while the pH ofthe aqueous polymer dispersion is 7 or less; this condition iscontemplated to be useful, for example, when some or all of thepolyvalent metal cation is in the form of an insoluble metal compound.In other embodiments, the subsequent admixture is formed while the pH ofthe aqueous polymer dispersion is higher than 7.

Also contemplated are embodiments in which all or part of the swellingagent and all or part of the polyvalent metal cation are addedsimultaneously to aqueous polymer dispersion. The ingredients may beadded at any concentration or feed rate. Such a method is considered tobe an embodiment of the present invention if, at some point during thesimultaneous addition, 1 to 10 parts by weight (based on 100 parts byweight of the monomer mix used to form the aqueous polymer dispersion)of swelling agent is present in the admixture at a time when the ratioof equivalents of polyvalent metal ions in the admixture to equivalentsof carboxylic acid functional groups in the admixture is 0.25 or less,and if, in the admixture after the addition of swelling agent andpolyvalent metal cation is finished, the ratio of equivalents ofpolyvalent metal ions in the admixture to equivalents of carboxylic acidfunctional groups in the admixture is 0.4 or more.

In some embodiments, after the formation of the subsequent admixture, nofurther swelling agent is added to the composition. In otherembodiments, some portion of at least one swelling agent (for example,one or more plasticizers, one or more coalescents, or one or more ofeach) is added to the composition after the formation of the subsequentadmixture.

In some embodiments, the composition of the present invention alsoincludes one or more basic salt of an alkaline metal. Basic salts ofalkaline metals include, for example, sodium hydroxide, potassiumhydroxide, and mixtures thereof. In some of the embodiments in which oneor more basic salt of an alkaline metal is used, the molar ratio ofpolyvalent metal cation to alkaline metal in the composition is 0.1 to10. In some embodiments, small amounts of alkaline metal are present inthe composition; in such embodiments, the molar ratio of alkaline metalto polyvalent metal cation in the composition is 0.02 or less; or 0.01or less; or 0.005 or less. In some embodiments, no basic salt of analkaline metal is used.

In some embodiments, the composition of the present invention containsingredients, known herein as “adjuvants,” in addition to those describedherein above. Adjuvants, when present, include, for example, waxes(including, for example, wax emulsions), surfactants, wetting agents,emulsifying agents, dispersing agents, leveling agents, cosolvents,thickeners (including, for example, alkali swellable resins and alkalisoluble resins), and mixtures thereof. Adjuvants, when present, may beadded at any point in the formation of the composition of the presentinvention. Some adjuvants, for example, may be added as part of theprocess of forming the aqueous polymer dispersion and will remain in thecomposition. Some adjuvants, for example, may be added to one or more ofthe ingredients or to one or more of the admixtures, to improve theproperties of the composition. Some of these adjuvants may reside in anyone of or any combination of the following locations: inside thesuspended particles of the aqueous polymer dispersion, on the surface ofthe suspended particles of the aqueous polymer dispersion, or in thecontinuous medium.

In some embodiments, one or more amphoteric surfactant is included inthe composition. In other embodiments, no amphoteric surfactant is used.

In some embodiments, one or more surfactant is added to the compositionafter the formation of the aqueous polymer dispersion. Such surfactantis herein called “cosurfactant.” Cosurfactant, if present, is inaddition to any surfactants that may have been used in the production ofthe aqueous polymer dispersion. One or more cosurfactant may be added tothe composition of the present invention at any point in the process offorming the composition, including, for example, one of, or anycombination of, the following points: cosurfactant may be admixed withaqueous polymer dispersion before aqueous polymer dispersion is admixedwith swelling agent; cosurfactant may be admixed with swelling agentbefore aqueous polymer dispersion is admixed with swelling agent;cosurfactant may be admixed with polyvalent metal cation complex beforepolyvalent metal cation complex is admixed with preliminary admixture.

Suitable cosurfactants may be any type of surfactant. Cosurfactants arepreferably chosen to be compatible with the aqueous polymer dispersionso as to avoid coagulating or otherwise degrading the aqueous polymerdispersion. Cosurfactants may be cationic, anionic, nonionic, or amixture thereof. In some embodiments, cosurfactants are nonionicsurfactants. Among the nonionic surfactants suitable as cosurfactantare, for example, alkoxylates, sulfates, sulfonates, phosphate esters,copolymers of ethylene oxide and propylene oxide, and mixtures thereof.Among the suitable alkoxylates are, for example, ethoxylates, which havethe structureR—O—(—CH₂CH₂O—)_(x)—Hwhere R is an aliphatic group, an aromatic group, analiphatic-substituted aromatic group, and aromatic-substituted aliphaticgroup, or a mixture thereof; and x is from 5 to 200. In some embodimentsR is alkyl-substituted benzene, with the structure R¹-R²—, where R¹ is alinear alkyl group and R² is an aromatic ring. One suitable cosurfactantis octylphenol ethoxylate. In some embodiments, R is an alkyl group,attached to the oxygen atom either at the end carbon or at anothercarbon. Mixtures of suitable cosurfactants are suitable.

Among embodiments in which cosurfactant is used, the amount ofcosurfactant can be characterized by the ratio of the solid weight ofcosurfactant to the solid weight of swelling agent. In some embodiments,this ratio is 0.05 or more; or 0.1 or more; or 0.2 or more; or 0.4 ormore. Independently, in some embodiments, this ratio is 10 or less; or 5or less; or 2 or less; or 1 or less.

While the invention is not limited to any particular mechanism ortheory, it is contemplated that the polyvalent metal cations and thecarboxylic acid functional groups are, in some embodiments, capable ofinteracting in a way that provides the effect of crosslinking of thepolymer. The effect of crosslinking can, for example, provide one ormore desirable properties to the dried layer of the composition, suchas, for example, hardness, durability, other useful properties, or acombination thereof.

The compositions of the present invention are useful for a variety ofpurposes. In some embodiments, one or more layers of the composition isapplied to a substrate and is dried or allowed to dry. In someembodiments, such a layer of the composition resides mostly orcompletely on the surface of the substrate, and the composition isconsidered a coating. In some embodiments, the subsequent admixture,optionally further admixed with one or more adjuvants, is intended foruse as a coating and is known as a coating material.

For example, one or more layers of the composition of the presentinvention may be applied to any of a wide variety of substratesincluding, for example, leather, roofs, and floors.

In some embodiments, a coating material that contains a composition ofthe present invention is used to coat a floor. Such a coating materialis known herein as a “floor polish.” Some floor polishes contain one ormore adjuvants; common adjuvants in floor polishes include, for example,wax emulsions, alkali soluble resins, wetting agents, emulsifyingagents, dispersing agents, defoamers, leveling agents, and mixturesthereof. In some embodiments, a floor polish contains an aqueous polymerdispersion with average particle diameter of 100 nm or larger, or 130 nmor larger. Independently, in some embodiments, a floor polish containsan aqueous polymer dispersion with average particle diameter 300 nm orsmaller; or 200 nm or smaller; or 150 nm or smaller. Independently, insome embodiments, a floor polish contains an aqueous polymer dispersionwith average particle diameter 75 nm or larger; or 100 nm or larger.Independently, in some embodiments, a floor polish contains an aqueouspolymer dispersion that is made by emulsion polymerization.

Embodiments of the present invention that are used as part or all of afloor polish (“floor polish embodiments”) include, for example,embodiments in which the Tg of the polymer is 35° C. or higher; or 40°C. or higher. Independently, in some floor polish embodiments, the Tg ofthe polymer is 70° C. or lower; or 65° C. or lower. Independently, insome floor polish embodiments, the Tg of the floor polish formulation(including all ingredients, including polymer, swelling agent, adjuvantsif used, etc.) is higher that 25° C.

It is to be understood that for purposes of the present specificationand claims that the range and ratio limits recited herein can becombined. For example, if ranges of 60 to 120 and 80 to 110 are recitedfor a particular parameter, it is understood that the ranges of 60 to110 and 80 to 120 are also contemplated. For another example, if minimumvalues for a particular parameter of 1, 2, and 3 are recited, and ifmaximum values of 4 and 5 are recited for that parameter, then it isalso understood that the following ranges are all contemplated: 1 to 4,1 to 5, 2 to 4, 2 to 5, 3 to 4, and 3 to 5.

EXAMPLES Example 1 Preparation of Latex Polymer

An emulsified monomer mixture was prepared by slowly adding thefollowing monomers in sequence to a stirred solution of 117.5 g of a 23%(by weight) solution of sodium dodecylbenzene sulfonate in 2100 g ofdeionized water: 1980 g butyl acrylate (BA), 2970 g methyl methacrylate(MMA), 3150 g styrene (Sty), and 900 g methacrylic acid (MAA).

In a reaction vessel equipped with thermometer, condenser, and stirrer,a solution of 4250 g deionized water and 156.5 g sodium dodecylbenzenesulfonate solution (23% by weight in water) and 30 g sodium sulfate washeated to 87° C. under nitrogen. A 225 g portion of the monomer mixturewas added all at once to the reaction vessel, and the temperature wasadjusted to between 80° C. and 82° C. A solution of 39 g ammoniumpersulfate in 90 g deionized water was made and then added all at onceto the reaction vessel. After an exotherm of 2° C. to 3° C. had ceased,the remaining monomer mixture was gradually fed to the reaction mixturealong with a cofeed solution (7.5 g ammonium persulfate, 50 g ammoniumbicarbonate, and 340 g deionized water). The rate of addition was chosenso that the temperature remained between 80° C. and 84° C. Afteradditions were complete, the containers and feed lines were rinsed tothe reaction vessel, and the contents of the reaction vessel were cooledto 40° C.

Example 2 Aqueous Polymer Dispersions

The following monomer mixes were prepared: Monomer parts⁽¹⁾ parts⁽¹⁾parts⁽¹⁾ parts⁽¹⁾ Mix BA Sty MMA MAA A 28 35 27 10 B 28 35 25 12 C⁽⁷⁾ 2235 33 10note⁽¹⁾parts by weight, based on 100 parts by weight of monomer mixnote⁽⁷⁾Polymer C was the monomer mix used in example 1.

Comparative Examples 2C and 3C; and Examples 4-6 Zinc Uptake Test

A zinc complex was formed by mixing 368.82 g zinc oxide, 423.15 gammonium bicarbonate, 423.15 g ammonium hydroxide solution (28% byweight in water), and 1125 g deionized water.

Using the methods of Example 1, latex polymers were made from themonomer mixes described in Example 2.

A variety of admixtures were formed. The polymers and swelling agentsvaried, as shown in the table below. The cosurfactant was a nonionicsurfactant. Each latex polymer that was used is characterized by its“monomer mix” in the table below.

Each latex polymer was stirred at 40° C.; cosurfactant (if used) andswelling agent (if used) were gradually added over 20 minutes; and theadmixture was then stirred for an additional 10 minutes. With stirringat 40° C., the zinc complex was added gradually over 30 minutes, and theresulting admixture was stirred at 40° C. for 10 minutes. The amount ofzinc complex added was calculated to give the zinc amount shown in thetable below for each example. The admixture was cooled to roomtemperature (approximately 20° C.) and filtered through a 325 meshscreen. Then, each admixture was allowed to stand at room temperature(approximately 20° C.) overnight. Then each admixture was examined toobserve whether any precipitate had formed. It is contemplated that anyprecipitate was a zinc compound. Ex- Mono- Cosur- Swelling swellingprecipi- am- mer factant agent agent zinc tate ple Mix amount⁽²⁾ typeamount⁽²⁾ amount⁽³⁾ amount 2C⁽⁴⁾ A 0 none⁽⁹⁾ 0 0.39 large 3C⁽⁴⁾ B 0none⁽⁹⁾ 0 0.44 large⁽⁵⁾ 4 B 2 capro- 2 0.44 light⁽⁶⁾ lactam 5 B 2 capro-4.65 0.75 none lactam 6 C 2 note⁽⁸⁾ 4 0.90 nonenote⁽²⁾parts by weight of solid cosurfactant, based on 100 parts of monomer mixnote⁽³⁾ratio of equivalents of zinc to equivalents of carboxylic acid groupsnote⁽⁴⁾comparative examplenote⁽⁵⁾from the large amount of precipitate that was observed, it iscontemplated that the amount of zinc that remained in the compositionwas less than 0.4.note⁽⁶⁾from the small amount of precipitate that was observed, it iscontemplated that the amount of zinc that remained in the compositionwas more than 0.4.note⁽⁸⁾Texanol ™ from Eastman Chemical

Example 7 Floor Polish

Floor polishes were made by mixing the following ingredients in theorder shown in the following formulation. Ingredient Amount, kg (lbs)Water 11.81 (26.03) Kathon ™ CG biocide (1.5% by weight, in water) 0.01(0.03) Rhoplex ™ 1531 resin⁽⁹⁾ 1.60 (3.53) Ammonia (28% by weight, inwater) 0.11 (0.25) Masurf ™ FS-230 wetting aid (1% by weight, in 0.91(2.00) water)⁽¹⁰⁾ Diethylene glycol monoethyl ether 2.04 (4.50)Dipropylene glycol methyl ether 1.13 (2.50) Tributoxy ethyl phosphate1.47 (3.25) Latex polymer (46.3% by weight, in water) of 20.92 (46.13)Example 6 AC-316N wax emulsion (30% by weight, in water)⁽¹¹⁾ 3.05 (6.72)Epolene ™ E43N wax emulsion⁽¹²⁾ 2.28 (5.03) SE-21⁽¹³⁾ 0.02 (0.04)note⁽⁹⁾Alkali swellable resin, from Rohm and Haas Co.note⁽¹⁰⁾Fluorocarbon Wetting Aid from Mason Chemicalnote⁽¹¹⁾Polyethylene wax emulsion from Chemcornote⁽¹²⁾Nonionic polyethylene/maleic anhydride wax emulsion from Chemcornote⁽¹³⁾Silicone-based defoamer from Wacker

Example 8 Testing of Floor Polishes

The following test methods were used:

Coating Application and Testing: The method for applying the floorpolish (base coat or top coat) to substrates for testing purposes isdescribed in “Annual Book of ASTM Standards,” Section 15, Volume 15.04,Test Procedure ASTM D 1436 (2000). Test Method B (application ofemulsion floor polish with a hand applicator) was used.

Gloss and Recoat Gloss: The method for determining the gloss performanceof polish compositions is described in “Annual Book of ASTM Standards,Section 15, Volume 15.04, Test Procedure ASTM D 1455. A Gardner BykMicro-Tri-Gloss meter, catalog number 4520, was used to record 60° and20° gloss.

Recoatability: The method for determining the recoatability ofwater-based emulsion floor polishes is described in “Annual Book of ASTMStandards,” Section 15, Volume 15.04, Test Procedure ASTM D 3153.

Film Formation: A draw-down using 0.4 ml of the coating composition wasapplied by means of a 2 inch (5.08 cm) wide blade applicator (asspecified in ASTM D 1436), having a clearance of 0.008 inches (0.02 cm),to a length of 4 inches (10.16 cm) on a vinyl composition tile.Immediately after application of the polish, the tile was placed on alevel surface in a refrigerator at 10° C. The dried film was rated asfollows: Excellent - No crazing Very Good - Slight edge crazing Good -Definite edge crazing Fair - Definite edge crazing with very slightcenter crazing Poor - Complete edge and center crazing

Black Heel Mark and Scuff Resistance: The method for determining blackheel and scuff resistance is described in Chemical SpecialtyManufacturers Association Bulletin No. 9-73 was utilized, except thatcommercially available rubber shoe heels were used in place of therecommended 2″ (5.08 cm) rubber cubes. A black heel mark is an actualdeposition of rubber onto or into the coating, whereas a scuff markresults from physical displacement of the coating which appears as anarea of reduced gloss. Scuff and black heel marks can occurindependently or simultaneously at the point where the heel impacts thesubstrate; i.e., upon removal of a black heel mark, a scuff may bepresent.

Soil Resistance: The method for determining soil resistance is describedin the “Annual Book of ASTM Standards,” Section 15 Volume 15.04, TestProcedure ASTM D3206 (2002). This test method covers the determinationof soil resistance of floor polishes on test tiles. A carpet coveredroller is used to simulate the action of foot traffic. A synthetic soilis employed in conjunction with the roller.

The floor polish of Example 7 was tested. Also tested was a comparativefloor polish, which was a commercially available floor polish, which isbelieved to include a polymer that includes polymerized units ofacrylic, methacrylic, and/or styrene monomers and that has carboxylicfunctional groups; which is believed to include zinc ions; which isbelieved to be a composition different from the compositions of thepresent invention, and which is believed to be made by methods differentfrom the methods of the present invention.

The floor polishes were applied to substrates by the method describedherein above, and the results of the tests were as follows: PolishProperty Comparative Example 7 Gloss G-VG G-VG Recoat Gloss VG VGRecoatability VG VG Film Formation EXC EXC Scuff Resistance Good G-VGBlack Mark Resistance P-F VG-EXC Soil Resistance Fair Good

The rating terms in the above table were as follows, in order ofincreasing desirability: P=poor; P-F=poor-fair; F=fair; F-G=fair-good;G=good; G-VG=good-very good; VG=very good; VG-EXC=very good-excellent;E=excellent.

The floor polish of Example 7 is at least as good as the comparativefloor polish in every test, and the floor polish of Example 7 is betterthan the comparative floor polish at Scuff Resistance, Black MarkResistance, and Soil Resistance.

1. A composition comprising (a) at least one aqueous polymer dispersion,wherein said polymer is formed from a monomer mix comprising 5-50% byweight based on the weight of said monomer mix, of one or morecarboxylic acid functional monomers; (b) 1 to 10 parts by weight of atleast one swelling agent, based on 100 parts by weight of said monomermix; and (c) at least one polyvalent metal ion; wherein the ratio ofequivalents of polyvalent metal ions in said composition to equivalentsof carboxylic acid functional groups in said composition is 0.4 or moreto 1; and wherein said composition is formed by a process comprising thestep of forming a preliminary admixture of said dispersion (a) with someor all of said swelling agent (b), wherein said preliminary mixturecontains no polyvalent metal cation or said preliminary mixture containspolyvalent metal cation in an amount such that the ratio of equivalentsof polyvalent metal ions in said preliminary admixture to equivalents ofcarboxylic acid functional groups in said preliminary admixture is 0.25or less to
 1. 2. The composition of claim 1, wherein said preliminaryadmixture further comprises one or more nonionic surfactants.
 3. Thecomposition of claim 1, wherein said monomer mix comprises 7-15% byweight based on the weight of said monomer mix, of one or morecarboxylic acid functional monomers.
 4. The composition of claim 1,wherein said ratio of equivalents of polyvalent metal ions in saidcomposition to equivalents of carboxylic acid functional groups in saidcomposition is 0.6 or more to
 1. 5. The composition of claim 1, whereinsaid ratio of equivalents of polyvalent metal ions in said compositionto equivalents of carboxylic acid functional groups in said compositionis 0.7 or more to
 1. 6. The composition of claim 5, wherein saidpreliminary mixture further comprises at least one alkali metalhydroxide; wherein said monomer mix comprises 5-15% by weight based onthe weight of said monomer mix, of one or more carboxylic acidfunctional monomers; and wherein the ratio of equivalents of saidpolyvalent metal ions in said composition to equivalents of saidcarboxylic acid functional groups in said composition is 0.7 or moreto
 1. 7. The composition of claim 1, wherein said swelling agentcomprises at least one compound selected from the group consisting ofplasticizers, coalescents, surfactants, and solvents.
 8. The compositionof claim 7, wherein said swelling agent comprises at least one compoundselected from the group consisting of plasticizers and coalescents.
 9. Aprocess for forming a coated substrate, said process comprising thesteps of (a) applying to said substrate at least one layer of a coatingmaterial comprising the composition of claim 1, and (b) drying orallowing to dry said layer.
 10. (canceled)
 11. The composition of claim1, wherein said monomer mix contains no monomers with anysulfur-containing acid functional groups.
 12. The composition of claim1, wherein said monomer mix additionally comprises one or more vinylaromatic monomer.
 13. The composition of claim 1, wherein said monomermix additionally comprises one or more alkyl acrylate.
 14. Thecomposition of claim 1, wherein said monomer mix additionally comprisesone or more alkyl methacrylate.
 15. The composition of claim 14, whereinsaid monomer mix additionally comprises one or more alkyl acrylate. 16.The composition of claim 15, wherein said monomer mix additionallycomprises one or more vinyl aromatic monomer.
 17. The composition ofclaim 16, wherein said monomer mix contains no monomers with anysulfur-containing acid functional groups.
 18. The composition of claim1, wherein said monomer mix additionally comprises one or more vinylaromatic monomer, butyl acrylate, and methyl methacrylate.
 19. Thecomposition of claim 18, wherein said monomer mix contains no monomerswith any sulfur-containing acid functional groups.